Radiologic evaluation of heat-induced shrinkage and shape preservation of human teeth using micro-CT

IntroductionThe most reliable and frequently applied method for identification of fire victims is comparative dental radiography. Forensic investigators are often confronted with fragmented and isolated remains, frequently removed from their anatomical position. Whilst the heat-induced dimensional and morphological changes in bone have been previously studied, precise data for heat-induced changes of human teeth is still lacking.ObjectiveThe aim of this study was to obtain quantitative micro-CT data to evaluate the three-dimensional shrinkage and shape preservation of human teeth to provide an improved understanding on heat-induced alterations of dental tissues.Materials and methodsHigh-resolution micro-CT scans and digital radiographs were carried out on 66 freshly extracted human teeth before and after 30 min exposure to temperatures of 400–1000 °C. Image analysis was performed using 3D Slicer and Fiji imaging packages.ResultsThe average volumetric shrinkage ranged between 4.78% (at 400 °C) and 32.53% (at 1000 °C). A major increase in shrinkage occurs between 700 °C and 800 °C, while no significant statistical difference (ANOVA post-hoc LSD, α<0.05) was found between lower temperature groups. Tooth morphology was generally well preserved even at high temperatures, in contrast to observation made for burned bone, where warping and strong deformation can occur.ConclusionsThe results of this micro-CT study add relevant information on shape preservation and allow forensic investigators to account for heat-induced alterations of size, eventually facilitating the odontological identification process in cases where only isolated teeth or dental fragments are present.